<p>Chickens were orally infected with the strains here tested on the 15 day of age. Samples of caecal tonsils and spleen tissues were collected at 1, 3 and 5 dpi. (*) This symbol shows groups whose mRNA transcription statistically differs by one-way ANOVA followed by Tukey’s test (* <i>P</i> < 0.05 / ** <i>P</i> < 0.01). CXCLi2: CXC-like chemokine previously named as interleukin 8; IL6: Interleukin 6; IFN: Interferon gamma; (CT): Caecal tonsil; (SP): Spleen; Control: Non-infected chickens; SP449/87: Chickens infected with <i>S</i>. Pullorum str. 449/87 (pullorum disease positive control); SG287/91: Chickens infected with <i>S</i>. Gallinarum str. 287/91 (fowl typhoid positive control); SGΔ<i>ccmH</i>: Chickens infected with SGΔ<i>ccmH</i>; SGΔ<i>idnTO</i>: Chickens infected with SGΔ<i>idnTO</i>; SGΔ<i>ccmHidnTO</i>: Chickens infected with SGΔ<i>ccmHidnTO</i>.</p
